Patrick Cantlay, a tall and slender 20-year-old, is the next big thing in professional golf, which is why he received a sponsor's exemption to compete in the star-studded AT&T Pebble Beach National Pro-Am.

But for a lonely, brutal stretch Saturday, the former two-time All-American at UCLA looked like a weekend hacker, playing the part of mere mortal on moving day. He was, at times, a man cursed by his clubs and an attackable course in near-perfect scoring conditions.

His roller-coaster round included an eagle on the second hole, five birdies, four bogeys and a triple-bogey.

At times, he was worthy of hearty applause. Other times, only snickers and booing could be justified.

"I kept my emotions in check pretty well all day," said Cantlay, a Las Alamitos native who was the main attraction at the Western Intercollegiate at Pasatiempo Golf Club the past two years. "There was a really rough stretch. I hit some really loose shots and the golf course has some teeth on those holes and it got me."

Which Cantlay shows up Sunday remains to be seen: Will it be the player who won four tournaments as a college freshman and spent a record 55 weeks as the No. 1 player on the World Amateur Golf Ranking or the hacker who shot 5-over on hole Nos. 13-15, including a triple-bogey 8 on No. 14?

To Cantlay's credit, he bounced back with birdies on holes Nos. 16 and 18 to stay in contention for a top-10 finish. It would be his first at a PGA event as a pro.

When sun dipped into the Pacific on Saturday, Cantlay -- who earlier in the day had climbed to second place -- was left with a disappointing even-par 72 and tied for 17th.

He enters Sunday's final round with a 6-under-par 208 total. That's six strokes behind co-leaders Brandt Snedeker and James Hahn.

Over the opening seven holes, Cantlay played like Tiger Woods in his prime, charging up the leaderboard with an amazing stretch of blue scores that included an eagle on the par-5, 502-yard second hole. He hit his hybrid on his approach shot from 235 yards out to five feet of the hole and drained his putt.

For good measure, he carded birdies three of the next five holes (Nos. 3, 4 and 7).

"Oh man, that was impressive," said Kelly Slater, an 11-time world champion surfer and Cantlay's amateur partner in the event. "He was on fire."

The flame fizzled, though. He posted bogey 5s on hole Nos. 8, 9 and 13 to crash back to earth.

"I was just thinking about hitting the next shot, trying to stay in the present and not worry about anything else," said Cantlay, noting his mentality didn't change, just his game did.

"It was hard to watch that 8 on 14," Slater said. "I was wishing it was me instead of him."

Through it all, Cantlay isn't out of it. We're talking about a player who shot 60 in the second round of the Travelers in 2011 -- still the lowest round shot by an amateur in a PGA Tour event.

He has the talent to turn a stellar round, as he indicated on the majority of the front side at Pebble.

Though he's set to compete on the Web.Com Tour this season, Cantlay has plenty of PGA experience from playing numerous events with an exemption. That's what prompted him to turn pro as a college junior despite not having a Tour card.

He made the cut in all five PGA events he competed in as a freshman and eight of 10 in 2012, including the U.S. Open at Olympic Club in San Francisco.

Saturday he made his first cut in three PGA events this season. And playing with an exemption is like playing with house money. Let's see how he cashes in.

"I don't really have any expectations," Cantlay said. "I try to stay in the present and play one shot at a time."

Spoken like a true pro.

He'll let his sticks do the talking. Hopefully, for his case, they speak volumes Sunday.